Solid fuel ducted rockets suffer performance degradation when operated under fuel-grain soak temperatures substantially different from baseline design conditions.
In general, such rockets rely on a fuel-rich solid propellant gas generator and a secondary combustion chamber whereby propellant gas or fuel gas generated from a solid substrate is fed through one or more interconnecting passages or throats to the secondary combustion chamber where it is combined with an oxidant to complete combustion and provide propulsive power thrust for the rocket.
Generation of such fuel-rich gas at the desired rate is difficult to optimize in such rockets (a) because of changing needs for propulsion power, the optimal amounts of fuel rich gas at any one time more or less depending upon the intended flight path of the rocket, and (b) because of sensitivity of the solid fuel mass flow rate to the solid propellant fuel grain temperature when using a constant nozzle throat area. These factors translate into performance penalties in the form of greater-than-necessary motor thrust margins, based on the lowest expected solid propellant temperatures, to assure adequate fuel gas flow rate.
It is an object of the present invention to minimize the need for excessive motor thrust margins and to obtain an energy efficient light weight, durable hydraulic/mechanical choke regulating device for continuously and automatically controlling actual and potential fuel gas generating rates within a solid fuel ducted rocket.